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Requirements for wooden floors

The guidelines are indicative and can be used in building cases by direct reference to this guide or as a starting point for own requirements in tender documents.

Assessment of wooden floors is done by handing in according to a contract agreement or by a corresponding handover with a customer. The assessment of the outcome requirements should be made according to the guidelines for visual assessment.

The outcome requirements apply under the following conditions:

1: When evaluating

Room temperature between 18 and 23º C. Humidity between 30 and 65% RH. Wood humidity: 8 ± 2%. That there is a balance between wood and air humidity. That the building is closed and heated. That the influence of floor heating is taken into account.

2: When laying *

Room temperature between 18 and 23 ºC. Humidity between 30 and 65% RH. Wood humidity: 8 ± 2%. That floors supplied from cold storage have been acclimated. The level of the subfloor is according to the supplier's instructions or TRÆ 64 Wooden floors - Laying.

(* It is assumed in new construction that measurements of concrete, wood and air humidity have been made over a period prior to and during the laying, and documented in the KS report (quality assurance report). floor heating system is correctly set.)


Performance requirements

  1. Is wood species, sorting, appearance and color as agreed?
  2. Have the planning requirements been complied with?
  3. Is the floor horizontal or with an agreed deviation from the horizontal as prescribed?
  4. Is the floor located at the prescribed head height?
  5. Is the floor without a level difference or with an agreed level difference in the joint between two floors?
  6. Does the floor have the prescribed strength and rigidity according to the prescribed load?
  7. Is the floor walkable / slip resistant as prescribed?
  8. Are joints between boards / rods uniform?
  9. Are any cross-curves in boards / rods (washing boards) below the acceptable level?
  10. Is the floor surface smooth and with the desired gloss?
  11. Is the floor free of annoying creaking sounds on the floor?
  12. Does the floor appear without defects, eg. without tears, marks, edge damage, loose rods, stains, discolorations or damage to surface treatment?
  13. Are cuts and joints closed and are adaptations to surrounding building parts and fixtures close?
  14. Are glued floors without defects regarding adhesion and sounds (screws)?
  15. Does the floor appear with a uniformly varnished, oiled or soap-treated surface?

Concepts, explanations and tolerances

Assessment of whether the outcome requirements have been met should be made, unless otherwise agreed, on the basis of the contractual basis for the delivery of the floor, and on the basis of the general industry guidelines for wooden floors mentioned below:

  1. For the assessment of wood species, sorting, color and appearance, a true-to-life floor test should be available, taking into account the effect of light on the wood. The assessment of color and appearance can be done according to the industry guide Wood Floors - Assessment of color differences.
  2. The flatness requirements for wooden floors are normally ± 2 mm measured with a 2 m straight and ± 0.6 mm on a 250 mm straight.
  3. Deviation from horizontal is determined by sloping the floor. Horizontal is measured from any point on the floor surface diagonally and perpendicular to the room walls, respectively. It is always recommended to agree tolerance for horizontality, especially for larger rooms. Unless otherwise agreed, the deviation from horizontal must not exceed ∆ = 10 mm at 6 meters. For logs of timber, with an average wood moisture content above 12%, it is to be expected that planar and horizontal will change as a result of the wood's drying and thus follow the joists' shrinkage and possible deflection. It should therefore be considered and agreed to the extent to which the requirement for planning and horizontality can be waived.
  4. Deviation from the head height measured by the outer limitation of the room and the entrance door (s): ± 3 mm
  5. Level difference in assembly between two similar wooden floors with the same longitudinal direction on joists (eg in door opening): Maximum 2 mm unless otherwise agreed. Larger level differences in joints between floors may occur due to differences in the underlying bearing structure (eg joists and concrete decks or two coulter floors), different floor coverings (eg tile floors and wooden floors), different laying direction (eg perpendicular on each other) or for coatings with their respective material and workmanship tolerances. Larger deviations in joints in hardwood floors can occur over time due to shrinkage and settlements in the substrate. Equalization with floor rail over joints is recommended.
  6. Requirements for strength and rigidity should be stated in the project material. The normal loads and designs for different application areas appear from TRÆ 64 and can be used in the assessment, where not otherwise specified. For compliance, see the guidelines for tolerances in WOOD 64.
  7. Any walking safety requirements should be measurably defined in the tender documents, eg. in connection with sports floors according to the supplier's instructions.
  8. Unless otherwise agreed, uniform joints are understood to mean: - The joints do not differ by more than ± 40% from the average joint width. - That smaller joints up to 0.6% of the width must always be accepted. - That some joints can be 0 mm wide. See Checklist for drop-out requirements and Guidance on joints in wooden floors in WOOD 64. Where joints are caused by width deviations, missing right-angled unit and side curvature, refer to tolerances stated in the supplier's product description. Unless otherwise specified, deviations according to tolerances are assessed at the time of delivery in TRÆ 63.
  9. Unless otherwise agreed, cross-curb (washboard) is equivalent to 0.3% of the width of solid floors and 0.15% of laminated floors, see TRÆ 63 for more information on measuring 'washboard' effect.
  10. Permissible landing and thickness deviations appear from the supplier's product description. Unless otherwise specified, deviations according to tolerances are assessed at the time of delivery in TRÆ 63.
  11. Repeated / repeatable sounds generally should not occur when traveling on floors, eg. due to failure of the substrate, in the fastening or from ferries and grooves, but 'voltage sounds' due to changes in air and wood humidity are accepted. Voltage sounds can occur on floors where there has been no traffic for some time, but usually disappears when driving. Creaking sounds from click floors occur if they are not folded sufficiently when laying.
  12. Assessment of deficiencies in floor surfaces should be done in accordance with guidelines for visual assessment in TRÆfakta 03: Wooden floors - Complaints. Assessment of possible discolorations, see industry guidelines TRÆfakta 06: Wooden floors - Assessment of color differences.
  13. Evaluated in relation to good workmanship, see also TRÆfakta 04 - Assessment of appearance and failure.
  14. Unless otherwise agreed, 'hollow sound' is accepted up to 10% of the floor surface area, provided evenly distributed. Areas with 'hollow sound' must be up to 0.1 m2 for board and parquet floors (with ferries / grooves) and up to 0.02 m2 for parquet floors (without ferries / grooves). For single rods no more than ¹ ³ ³ of length. Loose single rods must not occur.
  15. Pre-coated floors should appear with uniform, closed and smooth surfaces, oiled floors with a uniform surface and without edges, and soap-treated floors with a uniform surface and silk gloss. On brushed floors, there may be markings of structure, so they are not completely smooth. See also TRÆfakta about painting, lye treatment and oil treatment. Color, gloss and structural differences that are dependent on the properties and processing of the wood material must be accepted, as well as minor color differences in white pigmented surfaces.

Tolerances for flatness and horizontality have been prepared in collaboration with Dansk Byggeri and in accordance with the recommendations in www.tolerancer.dk.